The present invention relates to producing image data in a virtual set in which real image data is combined with synthesised virtual image data.
Procedures are known for generating three dimensional representations of objects and spaces and it is known for such representations to be used in many technical and artistic applications. With increasing processor power, it is possible to generate image data frames at broadcast video rate with increasing spatial definition. This allows a synthesised environment to be created which increasingly approaches the realism of a real environment and the overall process has become known as xe2x80x9cvirtual realityxe2x80x9d.
In addition to virtual reality applications, in which only a virtual world is seen, a process of combining real images with virtual or synthesised images, to produce a composite output, is disclosed in U.S. Pat. No. 5,479,597, assigned to the present applicant. In a virtual set, talent interacts with a synthesised background in real time and an environment of this type is licensed by the present applicant under the Trade Mark xe2x80x9cVAPOURxe2x80x9d.
An advantage of virtual sets is that large working environments may be perceived while talent is actually working within a relatively small studio. Furthermore, the number of applications for virtual sets increases as the reality of the virtual world, and hence the illusion of the combined result, is improved.
A problem with improving the reality of a virtual environment is that real environments have lighting effects due to the presence of real direct light sources. A real direct light source will illuminate real objects within a virtual set but it is not possible for such a light source to have similar effects upon virtual objects. Furthermore, great care must be taken when using direct light sources within a virtual set, given that the direct light may change the perceived colour of blue screen backgrounds resulting in the artefact known as xe2x80x9cspillxe2x80x9d.
According to a first aspect of the present invention, there is provided a virtual set in which real image data is combined with synthesised image data, including a real camera configured to generate said real image data; a real light source configured to direct light towards real entities within the set; synthesising means configured to synthesis virtual image data; combining means configured to combine said real data with said synthesised data; and co-ordinating means configured to co-ordinate said real light source with said synthesised light source so that real light and said synthesised light appear as if originating from substantially the same light source.
In a preferred embodiment, the set includes means for calibrating position transducers for said real light sources. Preferably, the calibrating means are calibrated by directing the real light sources at target position on virtual set walls. Alternatively, the position transducer calibrating means may be calibrated by directing the real light source at known planar surfaces in a virtual set, including means for analysing the shape of the resulting ellipses.
According to a second aspect of the present invention, there is provided a method of producing image data in a virtual set, in which real image data is combined with synthesised virtual image data, comprising the steps of lighting a real object by means of a real light source; synthesising the presence of a light source in said virtual image data; and co-ordinating said real light source with said virtual light source such that said real light and said virtual light appear as originating from a substantially common light source.